Ecology of the burrowing amphipod, Pontoporeia affinis, in Lake Michigan / by Wayne Paul Alley.

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It can be seen, then, that the macrobenthic groups associated with
Pontoporeia represent a composite of several species. Each species has
behavioral characteristics and environmental requirements that are
unique for its niche. These positive associations, as was indicated
earlier, may merely reflect the fact that the larger sampling areas of
the Ponar and Smith-McIntyre benthos samplers mask the patterns of
the microassociations and those regions within the lake that are preferred by Pontoporeia are also selected by the other macrobenthis groups o
SEASONAL DISTRIBUTION
During the present study the density of amphipods has been found
to change very little over a 24-hour period of time, and there appear to
be little changes with time in the average standing crop of amphipods
when all stations are combined.
Eggleton (1937) combined the monthly Pontoporeia counts for the
samples collected from Lake Michigan in 1931. He found a slight decline
in the density from May to June, a marked increase from June to July,
a seasonal maximum in August, and a sharp decline in the counts from
August to November. Treating his 1932 samples in the same manner he
found a reverse trend. The abundance of amphipods declined slightly
from April to June, decreased sharply from June to July, and then increased considerably from July to September. He concluded that the
dissimilarities which existed between the seasonal samples of the two
years reflected the natural tendency of any biological system to vary